Intravascular catheters are used in a wide variety of medical procedures by inserting the catheter into the vascular system of the patient at an easily accessible location. Thereafter, the tip of the catheter is advanced through the vasculature to a desired target site. In this manner, virtually any target site in the patient's vascular system may be remotely accessed. Of particular interest here are those medical procedures that require the use of injection catheters to inject therapeutic or diagnostic agents into various target tissues within the human body. When so used, an advantage of injection catheters is that the target tissue may be accessed by minimally invasive surgical techniques.
In many applications the target tissue is within a wall of an organ, such as the heart. For instance, therapeutic or diagnostic agents such as genes, proteins, or drugs may be injected directly into the heart. When the target tissue is within the wall of an organ, however, it is often desirable to inject the therapeutic or diagnostic agent into the tissue proximate the center of the organ wall. In these applications, if the needle of the injection catheter inadvertently passes through the wall, the therapeutic or diagnostic agents that are dispensed from the distal end of the needle will not be effectively delivered to the target tissue. Further, because the injection procedure often requires the thrust of a needle in the distal direction, the required motion can cause the catheter itself to contact and perforate or otherwise injure the wall of the organ.
In light of the above, it is an object of the present invention to provide a device and method that protects the myocardial wall from injury and perforation during an intra myocardial injection. Another object of the invention is to provide a device and method for controlling the depth of an intra myocardial injection. Still another object of the invention is to provide a device and method for performing an intra myocardial injection from a catheter in which a removable barrier prevents contact between the catheter and the myocardial tissue and allows the physician to advance the needle with confidence and without fear of perforating the myocardial tissue with the catheter. Yet another object of the present invention is to provide a device and method for performing intra myocardial injections which is easy to implement, simple to perform, and cost effective.